Adaptive Airway Treatment of Dorsal Displacement Disorders in Horses

ABSTRACT

A method of using an airway treatment system for treating a dorsal displacement disorder in a horse includes generating a treatment signal configured to treat the dorsal displacement disorder, using a pacemaker processor, in order to continuously stimulate one or more muscles involved in displacing a laryngeal anatomical structure relative to an airway of the horse, and using one or more stimulation electrodes, configured to interface with tissue of the horse, to deliver the treatment signal to the tissue of the horse a period of hours every day to maintain an unobstructed airway.

This application is a Continuation-in-Part of U.S. patent applicationSer. No. 14/216,455 filed Mar. 17, 2014, now U.S. Pat. No. 9,186,503,which is a Continuation of U.S. patent application Ser. No. 13/339,487filed Dec. 29, 2011, now U.S. Pat. No. 8,676,325, which is aContinuation-in-Part of U.S. patent application Ser. No. 11/962,667filed Dec. 21, 2007, which in turn claims priority from U.S. ProvisionalPatent Application No. 60/871,533, filed Dec. 22, 2006, the contents ofwhich are incorporated herein by reference in their entirety.

TECHNICAL FIELD

This application relates to relieving airway impairments in horses,specifically disorders associated with dorsal displacement of the softpalate.

BACKGROUND ART

FIG. 1 shows various anatomical structures associated with the head of ahorse. Among these, the airway structures, and in particular the larynxand pharynx, are susceptible to various disorders which affect thehorse's health and its ability to perform normally. The larynx isinnervated by the recurrent laryngeal nerves (RLN) which contain motorfibers that innervate both the abductor/opener and adductor/closermuscles of the arytenoid cartilages and their associated vocal folds.The soft palate normally fits closely around the ventral border of theepiglottis.

Airway impairment produces two symptoms, abnormal sounds and/or poorperformance. Abnormal sounds are detected by the human ear (riders,judges) and can be quantitate by time-frequency spectrogram. Horsesproduce inspiratory sounds characterized by three frequency bandscentered at approximately 0.3, 1.6, and 3.8 k Hz; See Derksen F J etal., Spectrum Analysis Of Respiratory Sounds In Exercising Horses WithExperimentally Induced Laryngeal Hemiplegia Or Dorsal Displacement OfThe Soft Palate, Am J Vet Res. 2001 May; 62(5):659-64, incorporatedherein by reference. Respiratory sounds of horses have been recordedusing a radiostethoscope such as that disclosed by Attenburrow et al.,Resonant Frequency of the Lateral Ventrical and Saccule and Whistling,Equine Exercise Physiology, pp 27-32, and in U.S. Pat. No. 4,218,584 toAttenburrow, both of which describe a stethoscope for detecting andrecording data from a horse while the horse is walking, trotting,cantering, jumping, and galloping. A transducer such as a microphone isattached to the animal's skin adjacent to the windpipe. The electricaloutput from the transducer is transferred to a radio transmitter mountedon the animal or its harness. The radio transmitter can transmit signalsa distance from the horse to allow for monitoring the horse's breathingfrom a distance. U.S. Pat. No. 6,228,037 describes a method andapparatus for recording and analysis of respiratory sounds in exercisinghorse, and U.S. Pat. No. 6,659,960 describes a method and system forcontinuous monitoring and diagnosis of body sounds, which discloses aportable unit for recording the upper airway respiratory sounds of anexercising horse to determine whether the horse suffers from an upperairway obstruction condition.

Some horses exhibit a disorrder of the upper airway known as dorsaldisplacement of the soft palate (DDSP). Pulmonary ventilation at rest isadequete, but during exercise the cross sectional area of the horsepharynx is reduced by collapse during exhalation. This results insignificant airflow reduction which is generally associated with anabnormal upper respiratory noise at exercise. In horses used forcompetition, the decreased volume of airflow interferes with performanceand may impair the horse's ability to compete. Although conventionalmethods of treatment have been useful in some horses, they are less thanideal since they have only modest success rates and significantcomplications.

The specific pathophysiology of DDSP is that during exercise horsesnormally interlock their soft palate and the epiglottis to form a directopen airway from the nasal cavity to the trachea. But in some horses,the soft palate displaces dorsally during exercise, the free end of thepalate then lies in the airway and causes a major obstruction to expiredair. The exact cause of DDSP is not known, however, it is believed to becaused by either direct mechanical displacement by posterior movementsof the tongue, or weakness in the muscles of the soft palate or thosethat raise the epiglottis or the entire larynx.

Several muscles are related to movement of the larynx and pharynx, butthe specific role of each is not well understood. US Patent Publication2007123950 described a twelve muscle model of the pharyngeal andlaryngeal airway and showed that neuromuscular stimulation of just oneor two of the muscles sufficed to move the hyoid bone. Two airwaymuscles could be coordinated synergistically to protect the pharyngealand laryngeal airway by a distance reduction of the hyoid complex andlarynx relative to the chin. Specifically, stimulating the thyrohyoidmuscle reduced the distance of the hyoid complex relative to the larynx.And geniohyoid muscle stimulation in combination with at least one othermuscle also generated the synergy of simultaneous reduction of distanceof the hyoid complex and the larynx relative to the chin. Multipleintramuscular electrodes were placed in two or more upper airway musclesand controlled by an implanted stimulation device.

Functional electrical stimulation (“FES”) refers to the application ofstimulation devices to nerves and muscles to treat medical disorders.Application of FES to paralyzed laryngeal muscles was introduced intohuman clinical otolaryngology in 1977 by Zealear D L, Dedo H H, ControlOf Paralyzed Axial Muscles By Electrical Stimulation, Acta Otolaryngol(Stockholm) 1977, 83:514-27, incorporated herein by reference. The mostsuccessful FES system to date is the cardiac pacer which has become aroutine part of cardiac disease therapy: Lynch, Cardiovascular Implants,in Implants, Lynch ed., Van Nostrand Rheinhold, New York 1982,incorporated herein by reference. However, there are a variety of otherFES systems, of which the most heavily researched are FES systems torestore locomotion to paraplegics and arm motion to quadriplegics:Peckham, IEEE Trans. Biomed. Eng. 1991, 28: 530, incorporated herein byreference. Other motor control devices restore bladder control toparaplegics and diaphragm function to high quadriplegics: Erlandson,Scand. J. Urol. Nephrol. 44 Suppl: 31, 1978; Glenn, Ann. Surg. 183: 566,1976, incorporated herein by reference. There also are FES devicesdesigned to rehabilitate the sensory deficits, such as the cochlearimplant: Hambrecht, Ann. Otol. Rhinol. Laryngol. 88: 729, 1979,incorporated herein by reference. To date such systems have not beendeveloped for horses which present different clinical conditions fromhumans.

An FES device for the equine applications must be effective and alsomust conform to the rules of the governing bodies that oversee equinesports. In thoroughbred and standard breed racing, this requires thatthe device must not give the horse an unfair advantage. In addition, itcannot allow tampering with the horse's performance. Specifically, aswagering is an integral part of the sport, there cannot be a way ofadjusting the device to manipulate the horse's performance.

SUMMARY OF THE EMBODIMENTS

Embodiments of the present invention are directed to treating a dorsaldisplacement disorder in a horse such as dorsal displacement of the softpalate, nasopharyngeal collapse, rostral displacement of thepalatopharyngeal arch, or epiglottic retroversion. A pacemaker processorgenerates a dorsal displacement disorder treatment signal responsive toat least one therapy parameter for treating the dorsal displacementdisorder. One or more stimulation electrodes interfaces with tissue ofthe horse for delivering the treatment signal to continuously orintermittently (coordination with breathing frequency) stimulate softpalate tissue of the horse during an entire period of increased activityof the horse.

The device or some portion of it may be incorporated into the racinggear of the horse. The device or some portion of it also may beimplanted in the horse. Any implanted portion of the device wouldcommunicate transcutaneously or percutaneously with the portion of thedevice located externally to the horse. For example, transcutaneouscommunication may be based on at least one of electromagnetic induction,acoustic energy, optical energy, and capacitor coupling. The device or aportion of it may be temporarily placed on the skin of the horse whenthe device is operating to provide external signals to the implantedportion of the device. The treatment signal may be derived from at leastone of an electromyogram, an electronystagmograph, anelectroglottograph, an electroencephalograph, a biopotential sensor, anultrasound sensor, a hall sensor, a microphone, a pressure sensor, astrain transducer, a mechanical deformation sensor, accelerometer and amotion sensor. The implanted portion may include a power source which ischarged percutaneously or transcutaneously.

The treatment signal may be applied to the tissue of the horse based ona signal derived from a biological function of the horse. The treatmentsignal may be applied to the tissue of the horse using a biphasicwaveform. The stimulation electrodes may be based on at least one of acuff electrode, a multipolar cuff electrode, a tripolar cuff electrode,a flat nerve electrode, an epineural electrode, a shaft electrode, alongitudinal intrafascicular electrode, a thin wire electrode, amicro-machined electrode, and a sieve electrode, any of which may becapable of differential activation causing stimulation to a specificarea of the upper airway tissue.

Specific embodiments may further include one or more sensor electrodesfor sensing at least one therapy parameter related to operation of thedevice. The therapy parameter may specifically relate to at least one ofair flow characteristics of the airway tract of a horse, contractilecharacteristics of the airway tissue of a horse, electricalcharacteristics of a portion of the body of the horse, blood gasesconcentration of the horse, temperature of a portion of the body of thehorse, pH of a portion of the body of the horse, chemical constituencyof a portion of the body of the horse, and physiological state of thehorse. The sensor electrodes may be placed externally on the horse,and/or implanted in the horse. The sensor electrodes may be connected tothe pacemaker by one or more leads and/or integrated into a housingcontaining the pacemaker processor. The treatment signal may further bea function of the one or more stimulation electrodes, or a horse expert,or some combination thereof. In specific embodiments, the sensorelectrodes may be implanted in the body of the horse, and/or may includean accelerometer which detects activity level of the horse.

In other specific embodiments, the therapy parameter may relate todelivery efficiency of the treatment signal by the one or morestimulator electrodes, for example, for at least one of vocal cordfunction, functioning of another segment of the upper airway tissue, andsome other parameter inside the horse's body. In addition oralternatively, the therapy parameter may include at least one ofpressure, contractile force, airflow rate, airflow pressure, airflowamount, airflow velocity, temperature, impedance, blood gasesconcentration, pH, and chemical constituency. The therapy parameter mayrelate to horse activity level based on at least one of cardiacactivity, respiratory activity, and electromyographic activity. Thetherapy parameter may relate to a posture or activity level of thehorse, such as whether the horse is asleep or awake.

The treatment signal may be a function of a regular periodic analysis ofthe therapy parameter, or an irregular non-periodic analysis of thetherapy parameter. The sensor electrodes may sense physiologicalconditions continuously or periodically. The pacemaker processor maycapture the therapy parameter at selected time intervals, which may beselected to conserve a power source associated with the system. Inaddition or alternatively, the pacemaker processor may capture thetherapy parameter in response to a user input from a user interface, forexample, based on a magnetic input from the user.

Specific embodiments may also include at least one sensor electrode forsensing the at least one therapy parameter. This may include at leastone of electrical stimulation, electrical bio-potentials from tissueactivity evoked by stimulation, vocal fold abduction, vocal cordadduction, and airflow changes related to vocal fold position. Thesensor electrode may sense vocal fold abduction by at least one ofmonitoring proper airflow based on at least one of airway sound,subglottic pressure, and temperature. A sensor electrode may also sensevocal fold movement based on vocal fold displacement, for example, bymeasurement with at least one of a laryngeal tissue strain gauge,trans-glottis light sensing, changes in laryngeal tissue impedance, andvideo observation of the vocal folds. The sensor electrode may senseinspiratory airflow interference such as by inspiratory airflowinterference based pressure associated with at least one of thesubglottis, the trachea, or extra-trachea intra-thorax. The sensorelectrode may sense inefficient respiration during exercise such as bysystemic physiologic signals including at least one of a decrease inblood oxygen and an increase in CO₂. The sensor electrode may include aradiostethoscope and/or a microphone transducer attached to thesubject's skin adjacent to the windpipe. For example, an external radiotransmitter may be in communication with the microphone transducer formonitoring the horse's breathing from a distance.

Embodiments of the present invention also include an airway treatmentsystem for treating a dorsal displacement disorder in a horse. Apacemaker processor generates a dorsal displacement disorder treatmentsignal during an exercise period of the horse based on anteriordisplacement of the tongue relative to the airway. One or morestimulation electrodes delivers the treatment signal to tissue of thehorse to control the anterior displacement of the tongue and maintainthe airway unobstructed during the exercise period. In specificembodiments, the tissue of the horse may include geniohyoid,genioglossus, and/or mylohyoid muscle tissue, and/or hypoglossal nervetissue.

Embodiments of the present invention also include an airway treatmentsystem for treating a dorsal displacement disorder in a horse. Apacemaker processor generates a dorsal displacement disorder treatmentsignal to strengthen one or more palatal muscles of a horse susceptibleto a dorsal displacement disorder. One or more stimulation electrodesdelivers the treatment signal to tissue of the horse to maintain theairway unobstructed during the exercise period. The tissue of the horsemay specifically include palatoglossus and/or palatopharyngeous muscletissue, and/or hypoglossal, vagal, and/or glossalpharyngeal nervetissue.

Embodiments of the present invention also include an airway treatmentsystem for treating a dorsal displacement disorder in a horse. Apacemaker processor generates a dorsal displacement disorder treatmentsignal during an exercise period of the horse based on displacement of alaryngeal anatomical structure relative to the airway. One or morestimulation electrodes deliver the treatment signal to tissue of thehorse to raise elevated and/or move rostrally the laryngeal anatomicalstructure and/or hyoid apparatus and maintain the airway unobstructedduring the exercise period.

The laryngeal anatomical structure may specifically include the larynxand/or epiglottis of the horse. The tissue of the horse may includethyrohyoideus, geniohyoid and/or mylohyoid muscle tissue. The tissue ofthe horse also may include nerve tissue to the palatoglossus,palatopharyngeous, and/or thyrohyoid muscle.

Embodiments of the present invention also include an airway treatmentsystem for treating a dorsal displacement disorder in a horse in which apacemaker processor generates a dorsal displacement disorder treatmentsignal to strengthen one or more muscles involved in displacinglaryngeal anatomical structure relative to the airway of a horse andsusceptible to a dorsal displacement disorder. One or more stimulationelectrodes then deliver the treatment signal to tissue of the horse tomaintain the airway unobstructed during the exercise period.

In further such embodiments, the laryngeal anatomical structure mayspecifically include the larynx, epiglottis, geniohyoid muscle tissue,mylohyoid muscle tissue, and/or nerve tissue to the palatoglossusmuscle, palatopharyngeous muscle, and/or thyrohyoid muscle. Displacementof a laryngeal anatomical structure relative to the airway may includereducing the distance between larynx and basihyoid bone, between thelarynx and the chin, and/or between the larynx, basihyoid bone and chinsimultaneously.

Embodiments of the present invention also include an airway treatmentsystem for treating a dorsal displacement disorder in a horse in which apacemaker processor generates a dorsal displacement disorder treatmentsignal to the sensory input of the temporomandibular joint innervation(trigeminal n), nasopharynx (glossopharyngeal and vagus n) and larynx(internal branch of the cranial laryngeal nerve), tongue (lingual n) toindirectly strengthen one or more muscles involved in displacinglaryngeal anatomical structure relative to the airway of a horse andsusceptible to a dorsal displacement disorder. One or more stimulationelectrodes then deliver the treatment signal to tissue of the horse tomaintain the airway unobstructed during the exercise period.

Embodiments of the present invention also include a method of using anairway treatment system for treating a dorsal displacement disorder in ahorse. The method includes detecting an elevated activity level of thehorse using one or more treatment sensors, generating a treatment signalbased on the detected elevated activity level, using a pacemakerprocessor, to strengthen one or more muscles involved in displacing alaryngeal anatomical structure relative to an airway of the horse, andusing one or more stimulation electrodes, configured to interface withtissue of the horse, to deliver the treatment signal to the tissue ofthe horse to maintain an unobstructed airway.

Embodiments of the present invention also include a method of using anairway treatment system for treating a dorsal displacement disorder in ahorse. The method includes generating a treatment signal configured totreat the dorsal displacement disorder, using a pacemaker processor, inorder to continuously stimulate one or more muscles involved indisplacing a laryngeal anatomical structure relative to an airway of thehorse, and using one or more stimulation electrodes, configured tointerface with tissue of the horse, to deliver the treatment signal tothe tissue of the horse for a period of hours every day to maintain anunobstructed airway

In some embodiments, the treatment signal may be delivered to the tissueof the horse for at least 30% or more of each day, and preferably atleast 50% or more each day. The laryngeal anatomical structure mayinclude the larynx of the horse and/or the epiglottis of the horse. Thetissue of the horse may include one or more of geniohyoid muscle tissue,mylohyoid muscle tissue, nerve tissue to the palatoglossus muscle, nervetissue to the palatopharyngeous muscle, thyrohyoid muscle tissue, andnerve tissue to the thyrohyoid muscle. The displacing of the laryngealanatomical structure relative to the airway may include a reduceddistance between larynx and basihyoid bone. The displacing of thelaryngeal anatomical structure relative to the airway may include areduced distance between larynx and chin. The displacing of thelaryngeal anatomical structure relative to the airway may include areduced distance between larynx and basihyoid bone and chinsimultaneously. The displacing of the laryngeal anatomical structurerelative to the airway may include a reduced distance between basihyoidand larynx and ventral aspect of the petrous temporal/basisphenoid bone.The method may further include recording the elevated activity levelusing the pacemaker processor. The method may further include monitoringthe elevated activity level using the pacemaker processor, and adjustingthe treatment signal based on the monitored elevated activity level. Themethod may further include monitoring the treatment signals using thepacemaker processor, and adjusting the treatment signal based on themonitored treatment signals. The one or more treatment sensors mayinclude an accelerometer, an electromyogram, an electronystagmograph, anelectroglottograph, an electroencephalograph, a biopotential sensor, anultrasound sensor, a hall sensor, a microphone, a pressure sensor, astrain transducer, a mechanical deformation sensor, and/or a motionsensor. The one or more stimulation electrodes may include a cuffelectrode, a multipolar cuff electrode, a tripolar cuff electrode, aflat nerve electrode, an epineural electrode, a shaft electrode, alongitudinal intrafascicular electrode, a thin wire electrode, amicro-machined electrode, and/or a sieve electrode. The one or morestimulation electrodes may be configured to cause stimulation to aspecific area of the tissue of the horse by differential activation. Thetreatment signal may be delivered continuously over a period of hoursuntil the system is turned off. The treatment signal may be furtherbased on air flow characteristics of the airway tract of the horse,contractile characteristics of the airway tissue of the horse,electrical characteristics of a portion of the body of the horse,temperature of a portion of the body of the horse, pH of a portion ofthe body of the horse, chemical constituency of a portion of the body ofthe horse, and/or physiological state of the horse. The method mayfurther include monitoring operation of the pacemaker processor using atreatment verification monitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows various anatomical structures in the head of a horse.

FIG. 2 shows of various functional blocks involved in representativeembodiments of an airway treatment system for horse airway disorders.

FIG. 3A-C shows some non-limiting examples of specific electrodearrangements that may be useful.

FIG. 4 an example of a sieve electrode used to contact the fibers ofregenerating nerves.

FIG. 5 summarizes for various possible specific electrode configurationsthe tradeoffs and relative interaction between electrode selectivity andinvasiveness to the affected tissue.

FIG. 6 illustrates various components for making parameter adjustmentsto an airway treatment.

FIG. 7 shows a radiographic assessment of the effects of musclestimulation on three laryngeal points.

FIG. 8 shows a D-strength duration curve over time for one set ofexperiments.

FIG. 9 shows D-VDR (50 Hz, 6 ms) for one set of experiments.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Embodiments of the present invention include systems and methods forstimulating upper airway tissue of horses to relieve airway disorderssuch as dorsal displacement of the soft palate (DDSP), various forms oflaryngeal and pharyngeal and nasopharyngeal collapse, or airwaynarrowing.

The exact cause of DDSP is not known, but it is believed to be caused byeither direct mechanical displacement by posterior movements of thetongue, or weakness in the muscles of the soft palate or those thatraise or otherwise mobilize the epiglottis, hyoid apparatus or theentire larynx. The existing standard therapy has been to raise theentire larynx closer to the hyoid bone structure. These techniques havemet with only limited success, especially in the long term.

Embodiments of the present invention are based on one or more specificstrategies: (1) controlling anterior movements of the tongue bycontinuous stimulation of geniohyoid (genioglossus) and mylohyoid muscleor the hypoglossal nerve, (2) affecting the muscles of the soft palateto make the muscles more fatigue resistant by continuous stimulation ofpalatoglossus, palatopharyngeous, or neighboring pharyngeal muscles orhypoglossal, vagal or glossopharyngeal nerve branches to these musclesnerve, and/or (3) raising and/or advance the epiglottis, hyoid apparatusor the entire larynx by continuous stimulation of geniohyoid and/ormylohyoid muscle or hypoglossal nerve and/or vagal or glossopharyngealnerve branches to the palatoglossus, palatopharyngeous, or neighboringpharyngeal muscles, and nerve branches to the thyrohyoid muscle. In thisembodiment, the FES either targets the effective muscles or the sensoryinput indirectly affecting the muscles controlling the aforementionedstructures. The continuous stimulation should be sufficient to transformthe muscle fiber type from a mainly fast muscle type (fiber type II) toa more or even mainly slow muscle type (fiber type I) in order toimprove the fatigue resistance in the muscles controlling thesestructures. For example, the continuous stimulation may be for a periodof hours every day, e.g., preferably, at least 30% or more of each day,or at least 50% or more each day.

Electrical Airway Treatment System

Embodiments of the present invention include an electrical airwaytreatment system having an implanted portion that performs one or morefunctions. For example, the implanted device may generate tissuestimulation signals either by independent electronics or by dependentprocessing of the signal from an external component. The implant alsomay record sensed signals such as those related to monitoring operationof the system. In some embodiments, one or more implants may bothstimulate and sense the surrounding tissue. Lead wires may be connectedin a detachable or non-detachable way for transferring the stimulationsignals to the electrodes or recording signals from the electrodesand/or the sensors.

FIG. 2 shows an example of various functional blocks involved inrepresentative embodiments of an airway treatment system 200 for horseairway disorders. A pacemaker processor 201 generates an electricaltreatment signal to be applied to upper airway tissue of the horse fortreating the upper airway disorder. The pacemaker processor 201 mayperform other useful functions, including without limitation, monitoringand analysis of stimulation signals, sensor signals, and/or othertreatment signals. The pacemaker processor 201 may also provide aprogrammable interface for adjusting other elements within the systemand control the functioning of such other elements.

The pacemaker processor 201 in FIG. 2 is an external element of thesystem, for example, in a housing on the skin of the horse or integratedinto the horse's harnessing. In other specific embodiments, thepacemaker processor 201 may be implanted within the horse. In anexternal embodiment such as the one shown in FIG. 2, the pacemakerprocessor 201 provides the treatment signal (as well as any othersignals useful for the implanted portion of the airway treatment system200, e.g., a power signal) to an external coil 202 which inductivelycouples the signal(s) to a corresponding internal coil 203. Such coilarrangements are similar to those which are well known in the field ofhuman cochlear implants.

The treatment signal received by the implanted coil 203 is input to astimulation module 204 which develops an electrical treatment signal forapplication by one or more stimulation electrodes 206 which interfacewith the targeted upper airway tissue associated with the upper airwaydisorder being treated. The stimulation module 204 may be turned on towork continuously until turned off. For example, the treatment signalgenerated to treat dorsal displacement disorder may continuouslystimulate one or more muscles involved in displacing the laryngealanatomical structure relative to an airway of the horse. The one or morestimulation electrodes 206 may deliver the treatment signal to thetargeted upper airway tissue for a period of hours every day to maintainan unobstructed airway. Preferably, the treatment signal is delivered tothe tissue of the horse for at least 30% or more of each day, or even atleast 50% or more of each day. Alternatively, the stimulation module 204may be triggered by a signal obtained from the animal including but notlimited to the following.

The embodiment in FIG. 2 also may include a sensor electrode 207 whichsenses one or more therapy parameters related to the operation of theairway treatment system 200. For example, airflow characteristics andother physiological data. The sensor electrode 207 signal is processedby a sensor module 208 which may provide feedback to the stimulationmodule 204 and/or back to the pacemaker processor 201 (e.g. via loadmodulation from the internal coil 203 back to the external coil 202).The feedback signal from the sensor electrode 207 may be used byexternal components of the system such as generally by the pacemakerprocessor 201, or more specifically by a treatment verification monitor209 which verifies proper operation of the airway treatment system 200,for example, to ensure compliance with wagering related safeguards whichmay be required by one or more regulatory bodies, or more generally,monitor operation of the airway treatment system 200 based oninformation received from various system components. The airwaytreatment system 200 may also include a record log 210 which recordsvarious information related to operation of the airway treatment system200 such as periodic values of the one or more therapy parameters fromthe sensor electrode 207.

Specific embodiments of the airway treatment system 200 may be totallyexternal on the horse, totally implanted, or have both the external andinternal components. Embodiments of a airway treatment system 200 withboth external and internal components can transfer information and/orenergy across the skin of the horse. The external components may befixed permanently to the skin of the horse, or placed temporarily whenthe stimulation module 204 is functional, or placed intermittently, forexample, to charge the implant battery 205, to program the stimulationmodule 204, or to turn the stimulation module 204 on and off.

Example embodiments include but are not limited to airway treatmentsystems 200 that transfer energy or information across the skintranscutaneously or percutaneously. Percutaneous systems have directwiring or equivalent hardware that transfers information and energyacross skin or mucosa. Generally, chronic foreign objects placed acrossskin or mucosa risk becoming infected. However, newer technologies knownin the art allow the in growth of skin or mucosa onto the surface of thewire to protect the percutaneous entry of the wires. For cosmeticpurposes, the percutaneous device may appear to be a decorativepiercing, such as earrings are used by humans.

Alternatively or in addition, the implanted and the external componentsof the airway treatment system 200 may be transcutaneously linked, forexample, as shown in FIG. 2 by an external coil 202 and a correspondinginternal coil 203. Besides an arrangement of electromagnetic inductioncoils such as that shown in FIG. 2, transcutaneous systems known in theart include acoustic energy, optical energy (e.g., U.S. Pat. No.5,387,259), and/or capacitor coupling approaches. There may be an energyand/or data transfer system which interconnects a transcutaneous linkwith a first implanted component, and a transducer system of the firstimplanted component and the second implanted component (for example thestimulation module 204). An example of such a airway treatment system200 includes but is not limited to a first inductive link from theexternal components to the first implanted coil 203 and an implantedconnection to an implanted second inductive link to the implantedstimulation module 204. This arrangement may be useful to change partsof the airway treatment system 200, for example, in the case ofmalfunctions or upgrades, or to have a 2 phase implantation procedure ofdifferent components of the airway treatment system 200.

Internal and components of the airway treatment system 200 also maycommunicate using ultrasonic vibrations or magnetic fields. For example,a magnetic coupler may add electrical energy to an inductivedemodulation module to directly power the implanted components, or acapacitor or rechargeable battery may receive such energy and store itfor later use.

External components can serve various functions such as changing oradapting parameters of the implanted portions of the airway treatmentsystem 200. The external components may be placed under or withinblinders or other racing gear of the horse. Besides the specificarrangement shown in FIG. 2, other examples of the external componentsmay include induction coils, electronic circuitry, radio telemetryequipment, a detecting system, a processor, and a power source (e.g., abattery). In specific embodiments, the external components may transmitelectrical power signals only (e.g., to recharge the implant battery205), data signals only (e.g., stimulation signals for the stimulationmodule 204), control signals only (e.g., controlling or changingparameters of implanted components such as the stimulation module 204,stimulation electrodes 206, and/or sensor electrode 207), or anycombination thereof.

The external and internal components require appropriate mechanicalfixation to remain attached during vigorous exercise. In addition,movement of the components stresses any wires leading to or away fromthe component potentially causing the wire to break. Examples of methodsof the external fixation include glues, tapes, sutures, magnets,piercings, bands around the animal, or utilizing existing equineequipment such as the bridle, blinders, mane tamer, and saddle. As anon-limiting example the external coil 202 may be placed on the bridleof a horse in the area overlying the implanted the implant coil 203.

The airway treatment system 200 may use an electromyogram (EMG) ofanother inspiratory muscle, and it may include: a) a sensor electrode207 adapted for electrical coupling to a normally functioning musclewhich contracts during inspiration, and for providing electrical signalsindicative of muscle activity thereof; b) a stimulation electrode 206for electrical coupling to a dysfunctional muscle; c) a pacemakerprocessor 201 to receive the sensing signals from the sensor electrode207 and provide the stimulating signals to the stimulation electrode206. The dysfunctional muscle, in pacemaker operation, is stimulated insubstantial synchronism with the activity of the normally functioningmuscle. A normally functioning muscle which contracts during inspirationcould be the contralateral healthy muscle, or the diaphragm muscle orother muscles showing a high correlation of their EMG to inspiratorysignals.

Or the airway treatment system 200 may be based on electronystagmography(ENG) and include: a) a sensor electrode 207 adapted for electricalcoupling to a normally functioning nerve which contracts duringinspiration and providing electrical signals indicative of nerveactivity thereof; b) a stimulation electrode 206 for electrical couplingto a dysfunctional muscle; c) a pacemaker processor 201 coupled toreceive the sensing signals from the sensor electrode 207 and forproviding the stimulating signals to the stimulation electrode 206 insubstantial synchronism with the electrical signals provided by thesensor electrode 207. The dysfunctional muscle, in pacemaker operation,is stimulated in substantial synchronism with the activity of thenormally functioning nerve. A normally functioning nerve which contractsduring inspiration could be the phrenic nerve or other nerves showing ahigh correlation of their ENG to inspiratory signals.

An airway treatment system 200 may be based on electroglottography (EGG)and may include: a) sensing electrodes 207 adapted for electricalcoupling to measure vocal fold contact area (calledelectroglottography—EGG). EGG involves a high frequency, low currentsignal passed between the vocal folds with the aid of electrodes.Sensing electrodes 207 are placed on either side of the thyroid laminaor closer to the vocal folds. EGG is based on the principle that tissueconducts current. Therefore, when the vocal folds touch, greater currentflows. The output of the electroglottographic recordings can be used todetermine when the vocal folds are closed or opened and how fast theyare closing or opened) for providing electrical signals indicative ofvocal fold opening; b) a stimulation electrode 206 for electricalcoupling to a dysfunctional muscle; c) a pacemaker processor 201 toreceive the sensing signals provided by the sensing electrodes 207, andfor providing the stimulating signals to the stimulation electrode 206.The dysfunctional muscle, in pacemaker operation, is stimulated insubstantial synchronism with the activity of the vocal fold openingsignal.

Or an airway treatment system 200 may be based on using anelectroencephalogram (EEG), and it may include: a) sensing electrodes207 adapted for measurement of electrical activity in the brain,recording from electrodes placed on, in or under the scalp, orsubdurally, or in the cerebral cortex with the sensing electrodes 207located in areas where the EEG represents an electrical signal(postsynaptic potentials) from a large number of neurons showing a highcorrelation to inspiratory signals during inspiration and for providingelectrical signals indicative of activity thereof; b) a stimulationelectrode 206 for electrical coupling to a dysfunctional muscle; c) apacemaker processor 201 to receive the sensing signals provided by thesensing electrodes 207, and for providing the stimulating signals to thestimulation electrode 206. The dysfunctional muscle, in pacemakeroperation, is stimulated in substantial synchronism with the activity ofthe normally functioning brain region activity.

Or an airway treatment system 200 may be based on biopotentials, and itmay include: a) sensing electrodes 207 to measure biopotentials forelectrical signals with a high correlation to vocal fold opening or theamount of airflow during inspiration; b) a stimulation electrode 206 forelectrical coupling to a dysfunctional muscle; c) a pacemaker processor201 to receive the sensing signals from the sensing electrodes 207, andfor providing the stimulating signals to the stimulation electrode 206.

Electrode Implementation

Implant system electrodes such as the sensing electrodes 207 and/or thestimulation electrode 206 can be placed on one or more of the nervebranches of the hypoglossal nerve to the genioglossus, geniohyoid,hyoepiglotticus; vagal or glossopharyngeal nerve branches to thepalatoglossus, palatopharyngeous, or neighboring pharyngeal muscles;nerve branches to the thyrohyoid muscle. Alternatively, the sensingelectrodes 207 and/or the stimulation electrode 206 can placed directlyin or around the above described muscles, or on, under, or in thevicinity of upper airway mucosa. Electrical stimulation signals are thenapplied to mucosa or the sensory nerves supplying mucosa to evoke aswallow or reflex motor changes.

For example, in the treatment of nasopharyngeal collapse, the sensingelectrodes 207 and/or the stimulation electrode 206 can be placed on oraround the nerve branch to the stylopharyngeus muscle that forms theroof of the nasopharynx and the palatopharyngeous muscle that forms thewalls of the nasopharynx. Or for treatment of epiglottic retroversion,the sensing electrodes 207 and/or the stimulation electrode 206 can beplaced on or around the nerve branch to the hyoepiglotticus muscle andstimulation applied to retract the epiglotttis anteriorly. Or thesensing electrodes 207 and/or the stimulation electrode 206 may beplaced on or around the hyoepiglotticus muscle. (NB: All muscles arebilateral here and may or may not need bilateral stimulation.)

The sensing electrodes 207 and/or the stimulation electrode 206 may beplaced on the skin or mucosa of the animal, or within the body closer tothe target tissue. For example, the sensing electrodes 207 and/or thestimulation electrode 206 may be directly adjacent to the target nervewhere they will be very efficient and avoid spreading current tosurrounding tissue. Multiple stimulation electrodes 206 can be placedaround the tissue such that differential activation of the stimulationelectrodes 206 can cause the current to flow through specific areas ofthe target, thereby activating a portion of the target. This may bereferred to as a steerable electrical field. An example of the use ofsuch a stimulation electrode 206 is to activate a portion of a nervecontaining the neurons to a specific muscle while leaving the remainingneurons unstimulated.

FIG. 3A-D shows some non-limiting examples of specific arrangements ofthe sensing electrodes 207 and/or the stimulation electrode 206 that maybe useful. For example, a pair of electrodes may stimulate small nervebranches to confirm their function, as shown in FIG. 3A, where theelectrodes are 2 mm apart and bent in order to hook and isolate smallnerves for stimulation.

Another type of less invasive electrode is the cuff electrode, anexample of which is shown in FIG. 3B. This kind of electrode can beplaced around the peripheral nerve or in the spinal cord like an opentube. The electrodes are thus positioned inside the cuff in closecontact with the nerve. But in such an embodiment, a contraction mayplace the epineurium covering the nerve between the electrode and thefibers. The epineurium works as a kind of electrical insulator, so thiswould reduce the recording signals and increases stimulation thresholds.

Multipolar cuff electrodes can be used for selective stimulation suchthat different fascicles of a nerve can be stimulated. For example, acuff electrode with one electrode ring each at the distal, proximal, andcentral positions of the tube may be useful for recording neural signalsand/or for nerve stimulation. For recording, multiple cuff electrodesallow suppression of the external noise sources such as line interfaceor bioelectrical muscle signals by using the electrode in combinationwith a specific amplifier configuration. For stimulation, thisconfiguration limits the spread of electric current outside the cuff.

An alternative embodiment uses a flat nerve electrode similar to a cuff,but with a flat cross section. For example, see D. J. Tyler, D. M.Durand, Functionally Selective Peripheral Nerve Electrode: StimulationWith A Flat Interface Nerve Electrode, IEEE Transactions On NeuralSystems And Rehabilitation, 2002 10(4), pp 294-303, incorporated hereinby reference. By flattening the nerve, the nerve fascicles are moreseparated and more selective stimulation and recording is possible. Thisalso improves selectivity. Another embodiment uses an epineuralelectrode which is sutured to the epineurium of the nerve, anarrangement which is that is very efficient and selective.

FIG. 3C shows an example of a shaft electrode which may be more invasivethan cuff electrodes (See, e.g., T. Stieglitz, M. Gross, FlexibleBIOMEMS With Electrode Arrangements On Front And Back Side As KeyComponent In Neural Prostheses And Biohybrid Systems, Transducers'01/Eurothe sensors XV, 358-361, 2001, incorporated herein byreference). The electrodes have a needle shape with multiple sides. Theelectrodes are inserted into the neural tissue for closer contactbetween the electrode side and the nerve fibers. One difficulty thoughis the implantation method because of the mechanical stiffness of theperipheral nervous system. Further approaches are under development toimprove the stability and the penetration properties of this kind ofelectrodes. Additionally new implantation tools would be useful.

A longitudinal intrafascicular electrode combines a loop of a thin wireelectrode with a filament loop including a thin needle. This needle canbe used for guidance to implant the thin film electrode longitudinallyinto the nerve. Only the thin wire electrode will be left into thenerve. Depending on the implantation of the electrode a high selectivitycan be achieved. See, e.g., K. Yoshida, D. Pellinen, P. Rousche, D.Kipke, Development Of The Thin-Film Longitudinal Intra-FascicularElectrode, Proceedings Of The 5th Annual Conference Of The InternationalFunctional Electrical Stimulation Society, pp 279-281, 2000,incorporated herein by reference. Limitation to a low number ofelectrode sites for longitudinal intrafascicular electrodes can beresolved by the use of polyimide substrates as shown in FIG. 9. Thenumber of electrodes can be increased by the use of micro-structuringtechnologies. Moreover, a reference electrode and ground electrodes maybe included on the substrate.

As an alternative to thin-film electrodes, micro-machined electrodesbased on silicon may be used as needle arrays. At least two approachesare under development. One approach uses a combination of sawing andetching to structure a wafer from the normal direction; see, e.g., R. A.Normann, E. M. Maynard, P. J. Rousche, D. J. Warren, A Neural InterfaceFor A Cortical Vision Prosthesis, Vision Research, 39, 2577-2587, 1999,incorporated herein by reference. The second approach structures a waferin planar direction; see, e.g., K. D. Wise, D. J. Anderson, J. F. Hetke,D. R. Kipke, K. Najafi, Wireless Implantable Microsystems: High-DensityElectronic Interfaces To The Nervous System, IEEE Proceedings (InvitedPaper) Vol. 93 No. 1, 2004, incorporated herein by reference. Thisallows combination of the electrodes and the electronics. Manyelectrodes can be placed on each needle. One drawback of this kind ofelectrode is that the basic structure is only an arrangement of needles.A batch is required to create an array. For the silicon electrodearrays, special implantation tools may be needed to implant the arraysat high speed.

One invasive kind of electrode is the sieve electrode; see, e.g., A.Ramachandran, O. Brueck, K. P. Koch, T. Stieglitz, System Test Of ASmart Bi-Directional Interface For Regenerating Peripheral Nerves,Proceedings 9th Annual Conference Of IFES Society, Bournemouth, pp425-427, 2004, incorporated herein by reference. This electrode will beplaced between two cut ends of a nerve trunk. For guidance and fixationto the nerve, silicone tubes may be placed on both sides of the sieve;see, e.g., P. Dario et al., Robotics As A Future And EmergingTechnology: Biomimetics, Cybernetics And Neuro-Robotics In EuropeanProjects, IEEE Robotics And Automation Magazine, Vol. 12, No. 2, pp29-45, 2005; and X. Navarro et al., Stimulation And Recording FromRegenerated Peripheral Nerves Through Polyimide Sieve Electrodes, JPeripher Nery Syst. 3 (2) pp 91-101, 1998, incorporated herein byreference. The nerve fibers then regenerate through the holes of thesieve electrode. Some of the holes may be constructed with ringelectrodes to contact the nerve fibers. With regards to implantation,the applications for such electrodes include amputees and basicresearch; see, e.g., P. Dario et al., Neural Interfaces For RegeneratedNerve Stimulation And Recording, IEEE Trans. Rehab. Eng, Vol. 6, No. 4,pp. 353-363, 1998, incorporated herein by reference.

FIG. 4 shows an example of a sieve electrode used to contact the fibersof regenerating nerves. By placing the micro sieve in the regenerationpathway, the fibers regenerate through the different holes of the sieveelectrode. Ring-shaped electrodes around the sieve holes can have aclose contact to this regenerated fibers. In that case, a selectivecoupling of the sensory and motor is possible; see, e.g., P. Negredo, J.Castro, N. Lago, X. Navarro, Differential Growth Of Axons From TheSensory And Motor Neurons Through A Regenerative Electrode: AStereological, Retrograde Tracer, And Functional Study In The Rat,Neuroscience pp. 605-615 (2004), incorporated herein by reference. As aresult, selective stimulation and recording of neural bioelectricalpotentials could be achieved. An example of an electrode that can steercurrent is the perineural ring electrode.

FIG. 5 summarizes for various possible specific electrode configurationsthe tradeoffs and relative interaction between electrode selectivity andinvasiveness to the affected tissue.

Possible Sensors Alternative to Electrodes:

Ultrasound sensing can also be used in an embodiment of a treatmentsystem 200 including: a) sensing electrodes 207 for ultrasound couplingto the vocal fold area or pharynx or the lungs or other regions in thebody having a movement or volume change with high correlation toinspiration; b) a stimulation electrode 206 for electrical coupling to adysfunctional muscle; c) a pacemaker processor 201 to receive thesensing signals provided by the sensing electrodes 207, and forproviding the stimulating signals to the stimulation electrode 206.

An embodiment of a treatment system 200 may be based on sensors that usethe Hall effect. The Hall effect refers to the potential difference(Hall voltage) on opposite sides of a thin sheet of conducting orsemiconducting material in the form of a ‘Hall bar’ (or a van der Pauwelement) through which an electric current flows. This is created by amagnetic field applied perpendicular to the Hall element. The potentialdifference is correlated to the strength of the magnetic field. Thestrength of the magnetic field can be influenced by the transmission ofthe magnetic field, by tissue changes or movement of tissue composed ofparts with different conductivity near the semiconducting Hall thesensor element, or by distance or orientation changes of the Hall thesensor and the source of the magnetic field relative to each other.

Another embodiment could have a treatment system 200 including: a) anoptional sensing microphone for generating an electrical signalrepresentative of activity in an internal sensing location coupling tothe vocal fold area, pharynx, lungs, or other regions in the body havinga movement or volume change with high correlation to inspiration; b) astimulation electrode 206 for electrical coupling to a dysfunctionalmuscle; and c) a pacemaker processor 201 to receive the sensing signalsprovided by the sensing microphone, and for providing the stimulatingsignals to the stimulation electrode 206. See, e.g., U.S. Pat. No.6,174,278.

An embodiment may also be a treatment system 200 based on pressuresensing including: a) an optional pressure sensor for generating anelectrical signal representative of activity in an internal sensinglocation coupling to the vocal fold area, pharynx, lungs, or otherregions in the body having a movement or volume change with highcorrelation to inspiration; b) a stimulation electrode 206 forelectrical coupling to a dysfunctional muscle; c) a pacemaker processor201 to receive the sensing signals provided by the pressure sensor, andfor providing the stimulating signals to the stimulation electrode 206.

A strain transducer can be used in a treatment system 200 including: a)a strain transducer for generating an electrical signal representativeof elongations or compression in an internal sensing location couplingto the vocal fold area, pharynx, larynx, thorax, lungs, or other regionsin the body having a movement or volume change with high correlation toinspiration; b) a stimulation electrode 206 for electrical coupling to adysfunctional muscle; c) a pacemaker processor 201 to receive thesensing signals provided by the strain transducer, and for providing thestimulating signals to the stimulation electrode 206.

Torsion or bending can also be used in a treatment system 200 including:a) a mechanical deformation sensor for generating an electrical signalrepresentative mechanical stress in an internal sensing location coupledto the vocal fold area, pharynx, larynx, thorax, lungs, or other regionsin the body having a movement or volume change with high correlation toinspiration; b) a stimulation electrode 206 for electrical coupling to adysfunctional muscle; c) a pacemaker processor 201 to receive thesensing signals provided by the mechanical deformation sensor, and forproviding the stimulating signals to the stimulation electrode 206.

For example, a torsion or bending based treatment system 200 could use apiezo-active material. Piezoelectricity is the ability of certaincrystals to generate a voltage in response to applied mechanical stress.The piezoelectric effect is reversible in that piezoelectric crystals,when subjected to an externally applied voltage, can change shape by asmall amount. The deformation, about 0.1% of the original dimension,typically is of the order of nanometers, but nevertheless finds usefulapplications such as in the production and detection of sound,generation of high voltages, electronic frequency generation, andultra-fine focusing of optical assemblies. In a piezoelectric sensor, aphysical dimension is transformed by an applied mechanical force whichacts on two opposing faces of the sensing element. Depending on thedesign of the sensor, different “modes” to load the piezoelectricelement can be used: longitudinal, transversal, and shear.

The piezoresistive effect differs from the piezoelectric effect. Thepiezoresistive effect describes the changing electrical resistance of amaterial due to applied mechanical stress. In contrast to thepiezoelectric effect, the piezoresistive effect only causes a change inresistance, but does not produce electrical charges. That is done by anadditional electrical circuit.

In a typical system, electrodes/sensors may be inserted into musclesthat attach to the same solid anatomical structure such as cartilage orbone available to the upper respiratory system. This allows for two axiscontrol of the attached solid anatomical structure when the muscles arestimulated.

In addition, the muscle groups of the equine upper respiratory systeminclude muscles that create forces where they are attached to the boneand that modify the resultant movement with respect to each other. Pairsof muscles may coordinate to create a complicated movement of thecommonly attached structure such as the hyoid bone. So even though theremay be many individual muscles attached to the same structure,electrical stimulation of just two muscles may produce normal movementor nearly normal movement. So rather than stimulating just one muscle,controlling two muscles together may be more effective; for example,stimulating the geniohyoid muscle together with a second muscle.Similarly, it may also be advantageous to stimulate three or moremuscles together as a group. For example, two muscles may be controlledtogether as a coordinated pair and then a third muscle included in thestimulation arrangement to apply a force that modifies or augments theeffects of the coordinated pair of muscles. Or a pair of opposingmuscles may be alternately stimulated and modified or controlled by athird muscle.

Specifically, it may be useful to electrically stimulate a near-centerattached muscle and an off-center attached muscle. For example,stimulation of the near-center attached geniohyoid muscle together withanother off-center attached muscle may usefully produce a reduceddistance of the hyoid complex and the larynx relative to the chin toprotect the airway. There may also be movement of other biaxialcartilages and bones of the upper airway by electrical stimulation oftwo or more coordinating muscles.

Two or more muscles may be stimulated using different voltages,currents, pulse patterns and periodicities. A given muscle may responddifferently between one animal and another. Still these differentindividual responses may be accounted and compensated for. for example,using feedback signals measuring the stimulation effects; for example, atwo-axis digital image of a portion of the upper airway may be used todetermine the effect of electrical stimulation of one or more muscles.Or a useful feedback sensing arrangement may be based on a directelectrophysiological measurement from another feedback electrode at aseparate location in the same muscle.

Among the potential target tissue locations for electrical stimulationand/or sensing are striated muscles attached to ligaments and tendonswhich move bones, or to cartilage. Examples of such potential locationsinclude without limitation the mylohyoid, thyrohyoid, geniohyoid,hyoglossus, palatopharyngeous, cricopharyngeus, inferior constrictor,superior constrictor, anterior and posterior bellies of the digastric,genioglossus, temporalis, levator veli palatini, tensor veli palatini,palatoglossus, inferior longitudinal and superior longitudinal musclesof the tongue, styloglossus, thyroarytenoid, lateral cricoarytenoid, andinterarytenoid muscles.

Useful combinations of multiple muscles include without limitation thebilateral mylohyoid muscle(s), the bilateral thyrohyoid muscle(s), thebilateral geniohyoid muscle, the unilateral mylohyoid muscle(s), theunilateral geniohyoid muscle(s), the unilateral thyrohyoid muscle(s),the geniohyoid and thyrohyoid muscle combination, the mylohyoid andthyrohyoid muscle combination, the geniohyoid and the mylohyoid musclecombination. Mylohyoid stimulation refers to stimulation that createsthyroid prominence movement closer to the chin and segmental tissueretraction. Geniohyoid stimulation refers to stimulation that createsinferior-anterior bulking of segmental tissue without producing tonguemovement or jaw lowering. Thyrohyoid stimulation refers to stimulationthat creates reduced distance between the hyoid complex larynx and aslight diagonal twisting of the thyroid prominence contralateral to theside of stimulation.

Thus DDSP treatment may be based on displacement of a laryngealanatomical structure relative to the airway to raise the laryngealanatomical structure and maintain the airway unobstructed during theexercise period. Specific examples of the raised laryngeal anatomicalstructure may without limitation include the larynx and/or epiglottis ofthe horse. The stimulated tissue may without limitation includegeniohyoid and/or mylohyoid muscle tissue. The tissue of the horse alsomay include nerve tissue to the palatoglossus, palatopharyngeous, and/orthyrohyoid muscle.

Embodiments of the present invention also include an airway treatmentsystem for treating a dorsal displacement disorder based on generating atreatment signal in order to continuously stimulate one or more musclesinvolved in displacing laryngeal anatomical structure relative to theairway of a horse and susceptible to a dorsal displacement disorder fora period of hours every day, e.g., for at least 30% or more of each dayor at least 50% or more of each day. Preferably, the treatment signal isgenerated during periods when an elevated activity level is notdetected. Specific examples of the laryngeal anatomical structure whichis treated may without limitation include the larynx, epiglottis,geniohyoid muscle tissue, mylohyoid muscle tissue, and/or nerve tissueto the palatoglossus muscle, palatopharyngeous muscle, and/or thyrohyoidmuscle. The displacement of the laryngeal anatomical structure relativeto the airway may include reducing the distance between larynx andbasihyoid bone, between the larynx and the chin, and/or between thelarynx, basihyoid bone and chin simultaneously.

FIG. 7 shows a graph of data measurements for one set of experimentsillustrating the effect of muscle stimulation on three laryngeal points.The measurements were taken radiographically showing in millimetersrostro-caudal movement versus dorso-ventral movement, comparing againstcontrol data for stimulation of the thyrohyoid muscle, the geniohyoidmuscle, and stimulation together of both the thyrohyoid and geniohyoidmuscles. FIG. 8 shows a D-strength duration curve over time for asimilar set of experiments, and FIG. 9 shows D-VDR (50 Hz, 6 ms) for aset of experiments.

Another small set of experiments tested treatments of horses withnaturally occurring DDSP exploring muscle pacing of the thyrohyoideousmuscle alone, the geniohyoideous muscle pacing alone, simultaneouspacing of the thyrohyoideous muscle and geniohyoideous muscle,hypoglossal nerve pacing (the hypoglossal nerve innervates allprotrusion and retraction muscles of the tongue including thethyrohyoideous and geniohyoideous), and simultaneous pacing of thethyrohyoideous muscle and hypoglossal nerve cuff. These experimentsdemonstrated that hypoglossal nerve stimulation co-contracts all thetongue muscles including protrusion and retraction muscles and causedeven more palatal displacements. Independent stimulation of thethyrohyoideous muscle, geniohyoideous muscle, or genioglossus musclereduced the number of palatal displacements.

Parametric Adjustment Techniques

In embodiments that include a sensor electrode 207, the pacemakerprocessor 201 and/or the stimulation module 204 may receive informationfrom the sensor electrode 207 via wireless telemetry. The sensorelectrode 207 may be an external component which is not implanted. Inalternative embodiments, the sensor electrode 207 may be integratedwithin the housing of the stimulation module 204 and/or the pacemakerprocessor 201, or be coupled to one or both of them via one or moreleads. FIG. 6 shows an embodiment in which an external processor 603also may transmit information to the treatment system 200, such asadjustments to stimulation parameters to be applied by the stimulationmodule 204. The adjustments may be made based on the informationreceived from the treatment system, for example, from the stimulationmodule 204 or the sensor electrode 207, or from a source external to thetreatment system 200 such as a horse expert human user 606 via aclinician terminal 604 user interface with the external processor 603,or some combination thereof.

In one specific embodiment, the pacemaker processor 201 may record thereceived information, analyze the information, and adjust stimulationparameters based on the information, or some combination thereof.Alternatively, the pacemaker processor 201 may record information andtransmit the information to the external processor 603 via a datanetwork 602. In this case, the external processor 603 analyzes theinformation to generate adjustments to system characteristics such asstimulation parameters, and transmits the adjustments to the treatmentsystem 200 for the pacemaker processor 201 for application to thestimulation module 204. One of skill in the art will also understand andappreciate that a separate processor responsible for analyzing thereceived information and proposing or instituting adjusted stimulationparameters could also be associated with the treatment system 200. Asused herein, “associated with” refers to a structure that is eitherhoused with or within a device, or attached to a device via a lead.

One or more of the clinician terminals 604 may be coupled to a datanetwork 602 to receive or access notifications of system operations suchas stimulation parameter adjustments which may be generated by thepacemaker processor 201 or the external processor 603. In oneembodiment, a clinician terminal 604 can be used by a clinician user 606to reject or approve stimulation parameter adjustments. In the case ofapproval, the treatment system 200 proceeds to have the pacemakerprocessor 201 make the adjustments to the stimulation parameters bydownloading or inputting the adjustments to the implanted thestimulation module 204, e.g., as a new stimulation program, newparameters, or parameter adjustments. Alternatively, the clinician user604 may require a clinical visit by the horse so that the clinician user604 may supervise the parameter adjustments using the clinician terminal604 or a separate user programmer device.

Data network 602 may take the form of a local area network, wide areanetwork or global network such as the Internet. An external processor603 may include a web server to generate web pages containing proposedparameter adjustments for viewing via the clinician terminal 604. Inaddition, the external processor 604 may include an email server fordelivery of email notifications 605 of proposed parameter adjustments.The clinician terminal 604 may be any client device coupled to the datanetwork 602, such as a personal computer, personal digital assistant,interactive television, mobile telephone, or the like. Using theclinician terminal 604, a clinician user 606 accesses web pagesgenerated by the external processor 603 and receives email notifications605 advising the clinician user 606 of new information or proposedparameter adjustments for the horse.

If the treatment system 200 itself (e.g., pacemaker processor 201)handles analysis of information and generation of proposed parameteradjustments, the adjustments and information still may be transmitted tothe external processor 603 so that a clinician user 606 may review theinformation and adjustments via the clinician terminal 604. In thiscase, the pacemaker processor 201 provides intelligence for analysis andadjustment, but the external processor 603 supports reporting andapproval, if necessary, prior to implementation of the adjustments. Inother embodiments, the external processor 603 provides the intelligencefor analysis and adjustment, as well as the reporting and approvalmechanism. In this case, the external processor 603 serves as a conduitfor collection and transmission of horse information and programming ofthe implanted stimulation module 204 to implement stimulation parameteradjustments. In some embodiments, approval by the clinician user 606will only be necessary for certain stimulation parameter adjustments;for example, adjustments of a greater magnitude than a pre-determinedlimit.

In some embodiments, stimulation parameter adjustments may be madeautomatically by the external processor 603, but in many circumstances,however, it will be desirable to obtain approval from the clinician user606 prior to downloading or inputting stimulation parameter adjustmentsinto the treatment system 200. For this reason, it is desirable that theexternal processor 603 supports the generation of email notifications605 and web pages containing detailed reports so that the clinician user606 has the information necessary to make a decision about stimulationparameter adjustment. The external processor 603 may manage informationand parameter adjustment decisions for multiple horses as well asmultiple clinicians. In each case, the external processor 603 and thetreatment system 200 cooperate to provide adaptive adjustment ofstimulation parameters applied by the stimulation module 604 formanagement of the disease.

The information obtained by the external processor 603 may be providedby the stimulation module 604, the sensor electrode 207, the horse 100,or some combination thereof. In the case of the stimulation module 204,the information may include operational information relating to thestimulation therapy delivered by the stimulation electrodes 205.Examples of operational information include battery status, chargingstatus, lead impedance, parameter sets applied by the stimulation module204, telemetry status, time since implant of the stimulation module 204,and information regarding the elapsed time since the stimulationparameters were adjusted. In some embodiments, the parameter sets caninclude details regarding the frequency, amplitude, and pulse width ofstimulation, cycling parameters, identification of the stimulationelectrodes 205 being used, and other similar parameters. Also, in someembodiments, the implanted stimulation module 204 may serve to receiveinformation from the sensor electrode 207 and forward the information tothe external processor 603. Alternatively, in other embodiments, thesensor electrode 207 may transmit information directly to the externalprocessor 603.

One or more sensor electrodes 207 may provide a variety of informationindicative of the level of efficacy achieved by the neurostimulationtherapy delivered by the stimulation module 204. The information may beany information relating to the function of the vocal cords, or anyother segment of the horse's airway tract, or any parameter inside thehorse's body. For example, the sensor electrode 207 may monitorparameters such as pressure, contractile force, flow rate, flowpressure, airflow amount, and the like. Other examples of sensedinformation include flow velocity, temperature, impedance, pH, orchemical constituency. Any of such information may reveal the effect ofthe neurostimulation therapy on the physiological function of the horse100. For example, if the sensor electrode 207 indicates excessivepressure, excessive contractile force, or involuntary flow (i.e.,leakage) in response to a set of stimulation parameters, it may bedesirable to dynamically adjust the stimulation parameters to reduce thepressure or contractile force, and thereby enhance efficacy.

In still other embodiments, one or more sensor electrodes 207 may beimplanted within a horse 100 to sense a physiological state of the horse100. For example, a sensor electrode 207 may be deployed to sensecardiac activity, respiratory activity, electromyographic activity, orthe like, as an indication of horse activity level. Such activity levelinformation, in conjunction with other information, may be useful indetermining adjustments to stimulation parameters. Other types of sensorelectrodes 207 also may detect a posture or activity level of the horse100. For example, an accelerometer may detect an elevated activitylevel, e.g., during exercise, while other sensors may detect whether thehorse 100 is sitting, standing, or lying down. In addition, some of theinformation obtained by such sensor electrodes 207, such as respirationactivity, may be analyzed to determine, e.g., whether the horse 100 issleeping.

Information obtained from the horse 100 includes information enteredinto the external processor 603 via a clinician terminal 604 having auser interface such as a set of buttons, a keypad, a touch screen, orother input media. Like the information obtained from the sensorelectrode 207, the information obtained from the horse 100 also mayindicate a level of efficacy achieved by the neurostimulation therapy.Other information obtained from horse 100 may indicate a physiologicalstate of the horse 100, such as an activity type (e.g., working, eating,sleeping), activity level (e.g., elevated activity level duringstrenuous or moderate exercise, or normal activity level while resting),or posture (standing, sitting, lying down). Input such as this can berelevant because the efficacy of particular stimulation parameters mayvary as the physiological state of the horse 100 changes. Informationregarding the comfort of the horse 100 may also be obtained. Forexample, discomfort can be noted and rated on a relative scale by aclinician user 606. In yet another embodiment, a clinician user 606 caninput information regarding the overall subjective feeling of the horse100 with respect to the stimulation therapy. This input could again bebased on rating the overall feeling on a relative scale.

Also, in some embodiments, a clinician user 606 may be permitted toenter horse preferences, e.g., based on subjective sensations experienceby the horse 100. For example, a clinician user 606 may enterinformation indicating that a stimulation level, e.g., amplitude, pulsewidth, or pulse rate, is unpleasant or even painful. In addition, aclinician user 606 may enter information for stimulation levels thatseems to have no perceived efficacy from the horse's perspective. All ofthe information obtained by the external processor 603 or the treatmentsystem 200 may be temporally correlated so that it is possible toevaluate the conditions experienced by a horse 100, e.g., at the time ofa significant event.

The adaptation logic may take the form of a function or set offunctions, expressed mathematically or in a lookup table, that weightvarious informational items with predetermined coefficients and sum theweighted items to produce a parameter adjustment. In one embodiment, theadaptation logic could be based at least in part on some combination ofsafety ranges (for example, determined by a manufacturer or theclinician user 604), efficacy of the stimulation, and battery life. Inanother embodiment, the adaptation logic includes weighting of all ofthe information received by the external processor 603 and/or thetreatment system 200 (e.g. stimulation module 204, sensor electrode 207,etc.). In a further embodiment, the adaptation logic could also includeweighting of other parameters input from the clinician user 606 eitherthrough initial programming of the external processor 603 and/or thetreatment system 200 (e.g., pacemaker processor 201). In one embodiment,the safety ranges, whether determined by a manufacturer or the clinicianuser 606, set the limits of the parameter adjustment and/or are weightedmost heavily by the adaptation logic.

The stimulation parameter adjustments may be expressed as an upward ordownward change in one or more parameters such as amplitude, pulsewidth, or frequency. The stimulation parameter adjustments may beexpressed as an absolute magnitude of adjustment or an incrementaladjustment. In other words, the stimulation parameter adjustments may beapplied in a single step in the amount specified by the output of theexternal processor 603. If the adaptation logic, upon analysis of theinformation, specifies an increase of 20 Hz in the frequency of thestimulation pulses applied by the stimulation module 204, then that 20Hz increase is proposed as an instant adjustment to the stimulationparameters. In some cases, an absolute adjustment may be limited eitherby the manufacturer or by the clinician user 606 to a maximum adjustmentto avoid instantaneous changes that cause abrupt discomfort for horse100.

Alternatively, the adaptation logic may simply indicate that an increaseis necessary, in which case a series of incremental increases areapplied at periodic intervals until the adaptation logic no longerindicates the need for an increase. For example, frequency may beincreased in 1 Hz increments for so long as the adaptation logicindicates the need for an increase. In this case, a hysteresis functionmay be built into the logic to avoid repeated up/down toggling of thestimulation parameters. The adjustments may be carried out at differentintervals, such as seconds, minutes, hours, and even days, subject tothe discretion of the clinician user 606. In addition to increases ordecreases in parameters, the adaptation logic also may indicate that theefficacy is within an acceptable range, and provide an output indicatingno need for adjustment.

In one embodiment, the external processor 603 may also determine andmodify the frequency of analyzing and adjusting the stimulationparameters. For example, upon implantation and soon thereafter, moreadjustment may be necessary or desirable to obtain the most beneficialstimulation settings. In one embodiment, the timing of when to analyzethe stimulation parameters can be determined at least in part byanalyzing the history of the stimulation parameters, and adjustmentthereof. Alternatively, the timing of the adjustment analysis can bepre-determined by the clinician user 606, the manufacturer, or both. Inyet another embodiment, the clinician user 606 treating the horse 100can indicate, based on a subjective analysis of the efficacy of thecurrent parameters, that the external processor 603 should analyze thestimulation parameters to determine if an adjustment is necessary.

In embodiments in which the external processor 603 or the treatmentsystem 200 are permitted to directly and automatically adjust thestimulation parameters, the information may be analyzed on a periodicbasis, e.g., at intervals on the order of seconds, minutes, hours, ordays. In some embodiments, the external processor 603 and the treatmentsystem 200 may apply different analysis modes. In a first mode, theinformation may be analyzed and adjustments made at relativelyinfrequent periodic intervals on the order of several hours or severaldays. In a second mode, the external processor 603 or the treatmentsystem 200 may operate in a more intensive analysis and adjustment modein which information is evaluated and parameters are adjusted veryfrequently until a desired level of efficacy is achieved. This second,more intensive mode may continue until the efficacy level is driven intoan acceptable range. The intensive mode may be entered when analysis inthe first infrequent mode reveals efficacy levels that requirestimulation parameter adjustments. Again, the adjustments made to thestimulation parameters in either mode may be performed automatically orsubject to approval by the clinician user 606.

In one embodiment, the external processor 603 can, without further inputor authorization from any other source, input and utilize the newstimulation parameters. As discussed above, another embodiment requiresapproval by the clinician user 606 through the external processor 603before the new simulation parameters can be instituted and utilized. Inyet another embodiment, the external processor 603 can send the newstimulation parameters to the clinician terminal 604 for review and/orapproval by the clinician user 606 treating the horse 100. Thisembodiment could allow the clinician user 606 treating the horse 100 tosubjectively compare the efficacy of the two stimulation parameters andpick which settings they prefer. Furthermore, a number of previousstimulation parameters could be stored in memory to allow the clinicianuser 606 treating the horse 100 to pick from them, or designate some asparticularly efficacious, particularly undesirable, or particularlyefficacious for one or more activity levels or types (i.e. aparticularly desirable setting for exercise).

The sensor module 208 and/or the sensor electrode 207 may be chronicallyimplanted within a horse 100 for use over an extended period of time. Inthis case, the sensor module 208 carries sufficient battery resources, arechargeable battery, or an inductive power interface that permitsextended operation. The sensor module 208 and/or sensor electrode 207may be implanted by minimally invasive, endoscopic techniques for anextended period of time or a limited period of time to captureinformation useful in analyzing and adjusting the stimulationparameters. In other words, the sensor module 208 and/or sensorelectrode 207 may be chronically implanted to support ongoing parameteradjustments over an extended course of therapy spanning several monthsor years, or purposefully implanted for a short period of time tosupport a one-time parameter adjustment or a small number of adjustmentsover a relatively short period of time, such as several hours, days, orweeks.

In some embodiments, the sensor module 208 transmits sensed informationcontinuously or periodically to the stimulation module 204 or theexternal processor 603. In this case, the sensor module 208 monitorsphysiological conditions continuously or periodically. Alternatively,the stimulation module 204 or the external processor 603 may triggeractivation of the sensor module 208 to capture information at desiredintervals. In some cases, triggered activation may occur when theclinician user 606 treating the horse 100 enters information into theexternal processor 603. Triggered activation of the sensor module 208may be useful in conserving battery life, if applicable, of the sensormodule 208 or the stimulation module 204. In each case, multiple sensorelectrodes 207 may be provided and dedicated to different parameters ordifferent locations within the horse 100.

Rather than immediately transmitting the information to the stimulationmodule 204 or the external processor 603, the sensor module 208 mayinitially store the information internally for subsequent wirelesstransmission 601. Hence, in some embodiments, the information may bestored within the sensor module 208, and later communicated to thestimulation module 204 or the external processor 603. In this case, thestimulation module 204 or the external processor 603 may interrogate thesensor module 208 to obtain the stored information for analysis andpossible adjustment of stimulation parameters. As a further alternative,triggered activation may be applied by the clinician user 604 treatingthe horse 100 in the form of a magnet swiped in proximity to the sensorelectrode 207, in which case the sensor monitor 208 will includeappropriate sensing circuitry to detect the magnet use.

An embodiment may include a monitoring server, a web server, an emailserver, a programming server, a network link, a horse database, or somecombination thereof. The horse database may store information formultiple horses 100 in an organized form that permits ready retrieval ofinformation for analysis, reporting, and historical archival. The webserver generates web pages that contain information obtained for one ormore horses 100, including information obtained from the externalprocessors 603. The information may be presented in a variety of formatsand levels of detail. Using a clinician terminal 604 equipped with a webbrowser, a clinician user 606 can view information contained in horsedatabase by accessing the web server. The web server also may beconfigured to execute database access commands to retrieve desiredinformation. In some embodiments, the information may be organized usinga hierarchy of XML tags. The information contained in the web pages alsomay include proposed stimulation parameter adjustments. The stimulationparameter adjustments may be generated by the external processor 603 orthe treatment system 200. A clinician user 606 may approve thestimulation parameter adjustments by clicking on a button within the webpage. Upon receipt of clinician approval, the treatment system 200 maythen proceed to interact with the external processor 603 to implementthe stimulation parameter changes in the stimulation module 204. The webpage generated by the web server also may offer the clinician user 606the opportunity to modify the proposed stimulation parameter adjustmentsbefore approval, e.g., using boxes, drop down menus, slider bars, radiobuttons, or the like. In this case, the treatment system 200 implementsthe stimulation parameter adjustments as modified by the clinician user606.

An email server provides email notifications 605 to the clinicianterminal 604, if desired. The email notifications 605 may report newlyacquired information for a particular horse 100, or proposed stimulationparameter adjustments for the horse 100. The email notifications 605 mayinclude links to web pages for approval or modification of the proposedstimulation parameter adjustments. Alternatively, in some embodiments,the clinician user 606 may approve stimulation parameter adjustments byreplying to the email notification 605. In either case, the proposedstimulation parameter adjustments are not implemented until approval isreceived. In other embodiments, however, it is conceivable thatstimulation parameter adjustments may be fully automatic, and notrequire approval by the clinician user 606, particularly if stimulationparameter adjustments are subject to pre-programmed limits within theexternal processor 603 or the stimulation module 204.

Some embodiments may be used to support clinical research. For example,the external processor 603, the treatment system 200 and the clinicianterminals 604 may permit clinical user 606 researchers to accessinformation obtained from implanted stimulation modules 204 for purposesof research, and not necessarily for adjustment of stimulationparameters. Rather, clinician user 606 researchers may access theinformation obtained from the external processor 603 and the treatmentsystem 200 via clinician terminals 604 to gather information in supportof short or long range research for formulation of improved or enhancedtherapies. In some embodiments, adaptation logic may be configured toapply particular algorithms such as genetic algorithms, Bayesianclassification, neural networks, or decision trees. In those cases,adaptation logic may be formulated to implement algorithms similar tothose described in U.S. patent application Ser. No. 10/767,674; U.S.patent application Ser. No. 10/767,922; U.S. patent application Ser. No.10/767,545; and U.S. patent application Ser. No. 10/767,692, each ofwhich is incorporated herein by reference.

Treatment Verification Monitoring

Related to the foregoing, there also is a need in horse racing to followthe rules of the governing agencies such that a treatment system 200 ortreatment method would not create an unfair advantage, disadvantage, orerroneous response. The therapeutic goal is to restore function withoutsupra-maximal or supra-physiological advantage. Accordingly, embodimentsmay allow various safeguards to not influencing wagering. A loggingsystem may document use and frequency of the stimulation protocol. Forexample, as shown in FIG. 2, a verification monitor 209 andcorresponding record log 210 may act as a logging system which allows anequipment person in the paddocks or the competition arena to readilyassess that the treatment system 200 is active and functioningappropriately. The logging system should be easy to monitor under theconditions of competition.

Embodiments also include a treatment system 200 that does not influenceother biological functions of the horse 100 apart from the airwaydisorder that is being treated. Specifically, it is undesirable that thetreatment system 200 would cause any other effects that could stimulateor impair the athletic performance of the horse 100. This is partlysatisfied by the design of the treatment system 200 discussed herein.However, a method of ensuring that there are no extraneous effects is totest the treatment system 200 and measure physiological parametersincluding but not limited to contralateral vocal cord abduction, heartrate blood pressure, respiratory rate, or the multiple otherphysiological parameters mentioned herein or known in the art.

And embodiments include methods to satisfy the spirit and rules ofagencies governing equine sporting events, including monitoring devicesand methods such as a verification monitor 209 and/or record log 210which allow calibration by an attending veterinarian only, where thestimulation parameters are fixed and can only be adjusted by race trackpersonnel or attending veterinarians. In addition or alternatively, theathletic governing authority can monitor the effect of the treatmentsystem 200 before, during, or after an athletic performance. Themonitoring authority may want to know that the treatment system 200 wason and delivering proper electrical stimulation, that the treatmentsystem 200 senses that the vocal fold was abducted, and that air waspassing unrestricted through the larynx during inspiration. Along theselines, a variety of physiological parameters may be sensed and stored(data logging in the record log 210) or transmitted outside the horse100. Examples of data logging of such information include withoutlimitation stimulation parameters; nerve action potentials; microphone,acoustic, or subglottic pressure monitoring airways; tracheal pressure;and vocal fold abduction reflected by electroglottography (EGG—laryngealimpedance to hi-frequency electrical fields). In addition, lightproduced by a source located on one side of the larynx may be sensed bya light the sensor located on the other side.

In one specific embodiment, an external signal can be produced when thetreatment system 200 is working; for example, a light on an outercomponent that is active and visible with proper stimulation. Anotherexample is a radio signal that can be sensed by receivers at a distance.In another embodiment, a separate lead and electrode stimulate anothermuscle of the horse 100 such that its effects were clearly visible,e.g., stimulation of the muscle that moves the auricle so that theauricle tilts or rotates when the treatment system 200 is active.

The sensor electrodes 207 and sensor module 208 may sense electricalstimulation, electrical biopotentials from nerve or muscle activityevoked by stimulation, mechanically sense vocal fold abduction, orchanges in airflow related to vocal fold position. Proper stimulationabducts the vocal fold and allows maximum airflow, which can bemonitored by the sound of the air moving through the airway, subglotticpressure, or temperature. Vocal fold movement can be sensed by vocalfold displacement as measured by any of various specific means such asstrain gauges in laryngeal tissue, the amount of light passing acrossthe glottis, changes in tissue impedance across the larynx, or directvisualization of the vocal folds with an in-dwelling video camera.Interference with inspiratory airflow may be sensed by pressure sensorsin the subglottis or trachea, or outside the trachea but within thethorax. Such pressure sensors would show abnormally high negativepressure as resistance to airflow increased due to a medially positionedvocal fold. Inefficient respiration during exercise would rapidly bereflected in systemic physiologic signals: blood oxygen decreasing andCO2 increasing.

Embodiments of the present invention include endoscopically controlled,minimally invasive positioning of an electrode or electrodes, whichreduces the surgical risks and at the same time allows an adjustment ofstimulation to the individual deficit of the patient in vocalization,breathing, and/or swallowing by stimulating opening, closing, and/orelevation of the larynx. Some embodiments may allow more than oneelectrode to be inserted (e.g., bilaterally, or separate electrodes foropening and closing, or larynx elevation). “Pull through” techniques maycall for reinforcement of the electrode structure to accommodate theresulting traction stress. One particularly gently technique is to pushin the electrode under endoscopic view. Endoscopic control andintraoperative stimulation assist in obtaining an optimal positioning ofthe electrodes (as in some of the examples described above). Bilateralelectrode placements further offer the advantage of improvedthree-dimensional electric dipole vectors for optimal stimulation whichmay further improve flexibility. Bilateral separately controlledelectrodes may also provide greater safety in case of device failure.For example, if one side fails, the other side may (partially)compensate until the patient receives clinical help.

Embodiments of the present invention also are directed to a minimallyinvasive, two-stage implantation procedure. First, an electrode isinserted. Then, a test stimulation session may be conducted over time,e.g., over several days, to show efficiency of the system. Whenefficiency is verified, a stimulator may also be implanted and theelectrode may be retracted out of the body without a complicatedsurgery.

Embodiments include the implantation of a stimulation electrode of thelarynx using minimal invasive endoscopic techniques. For example, oneembodiment uses straight tubular electrodes that may be inserted in a“pull back” procedure on an implanted thread that the electrode isattached to.

Embodiments of the present invention also permit a minimally invasive,two-stage implantation procedure. First, the electrode may be insertedas disclosed above, but the stimulator itself is not implanted duringthe same surgery, but is left outside the body. A test stimulationsession may then be performed over time (minutes, hours or severaldays), and if this test stimulation session shows efficiency, thestimulator may be sterilized and the housing of the pacer may beimplanted via the small subcutaneous tunnel into the subcutaneouspocket. In case the stimulation system is not efficient enough, theelectrode may be retracted out of the body without a complicated surgerysimply by pulling the electrode back so its tip leaves the skin.

Surgical tools may be traditional surgical tools for a thyrotomyapproach include known tools from veterinary and human surgicaltheaters, and/or new tools which may incorporate, for example,electrodes that are inflated for insertion and then deflated when infinal position by another part of the tool or by a kind of memoryeffect. These tools may be independent tools or part of an endoscopicsystem. Electrodes may be anchored, for example, by sutures, glue, orattached anchors which do not limit insertion but resist unwantedmigration.

Embodiments of the present invention allow an FES device to survive theharsh environment within the neck of a horse and work reliably formonths. In still further embodiments, an implanted device can signalwhen it is working properly so that it can be monitored by regulatoryofficials—and this can be confirmed before, during, and after anathletic event by other methods and devices that are embodiments of thisinvention.

Although various exemplary embodiments of the invention have beendisclosed, it should be apparent to those skilled in the art thatvarious changes and modifications can be made which will achieve some ofthe advantages of the invention without departing from the true scope ofthe invention.

What is claimed is:
 1. A method of using an airway treatment system fortreating a dorsal displacement disorder in a horse, the methodcomprising: generating a treatment signal configured to treat the dorsaldisplacement disorder, using a pacemaker processor, in order tocontinuously stimulate one or more muscles involved in displacing alaryngeal anatomical structure relative to an airway of the horse; andusing one or more stimulation electrodes, configured to interface withtissue of the horse, to deliver the treatment signal to the tissue ofthe horse for a period of hours every day to maintain an unobstructedairway.
 2. The method of claim 1, wherein the treatment signal isdelivered to the tissue of the horse for at least 30% or more each day.3. The method of claim 1, wherein the treatment signal is delivered tothe tissue of the horse for at least 50% or more each day.
 4. The methodof claim 1, wherein the laryngeal anatomical structure includes thelarynx of the horse and/or the epiglottis of the horse.
 5. The method ofclaim 1, wherein the tissue of the horse includes one or more ofgeniohyoid muscle tissue, mylohyoid muscle tissue, nerve tissue to thepalatoglossus muscle, nerve tissue to the palatopharyngeous muscle,thyrohyoid muscle tissue, and nerve tissue to the thyrohyoid muscle. 6.The method of claim 1, wherein the displacing of the laryngealanatomical structure relative to the airway includes a reduced distancebetween larynx and basihyoid bone.
 7. The method of claim 1, wherein thedisplacing of the laryngeal anatomical structure relative to the airwayincludes a reduced distance between larynx and chin.
 8. The method ofclaim 1, wherein the displacing of the laryngeal anatomical structurerelative to the airway includes a reduced distance between larynx andbasihyoid bone and chin simultaneously.
 9. The method of claim 1,wherein the displacing of the laryngeal anatomical structure relative tothe airway includes a reduced distance between basihyoid and larynx andventral aspect of the petrous temporal/basisphenoid bone.
 10. The methodof claim 1, further comprising: monitoring the treatment signals usingthe pacemaker processor; and adjusting the treatment signal based on themonitored treatment signals.
 11. The method of claim 1, furthercomprising detecting an elevated activity level of the horse sufficientto cause the dorsal displacement disorder.
 12. The method of claim 11,wherein the treatment signal is generated when the elevated activitylevel is not detected.
 13. The method of claim 11, further comprisingrecording the elevated activity level using the pacemaker processor. 14.The method of claim 11, further comprising: monitoring the elevatedactivity level using the pacemaker processor; and adjusting thetreatment signal based on the monitored elevated activity level.
 15. Themethod of claim 11, wherein the elevated activity level of the horsesufficient to cause the dorsal displacement disorder is detected withone or more treatment sensors.
 16. The method of claim 15, wherein theone or more treatment sensors includes an accelerometer, anelectromyogram, an electronystagmograph, an electroglottograph, anelectroencephalograph, a biopotential sensor, an ultrasound sensor, ahall sensor, a microphone, a pressure sensor, a strain transducer, amechanical deformation sensor, a motion sensor, or combinations thereof.17. The method of claim 1, wherein the one or more stimulationelectrodes include a cuff electrode, a multipolar cuff electrode, atripolar cuff electrode, a flat nerve electrode, an epineural electrode,a shaft electrode, a longitudinal intrafascicular electrode, a thin wireelectrode, a micro-machined electrode, a sieve electrode, orcombinations thereof.
 18. The method of claim 1, wherein the one or morestimulation electrodes are configured to cause stimulation to a specificarea of the tissue of the horse by differential activation.
 19. Themethod of claim 1, wherein the treatment signal is further based on airflow characteristics of the airway tract of the horse, contractilecharacteristics of the airway tissue of the horse, electricalcharacteristics of a portion of the body of the horse, temperature of aportion of the body of the horse, pH of a portion of the body of thehorse, chemical constituency of a portion of the body of the horse,physiological state of the horse or combinations thereof.
 20. The methodof claim 1, further comprising monitoring operation of the pacemakerprocessor using a treatment verification monitor.